Power factor is generally known as the ratio of the real power (P) to the apparent power (S) flowing in a load. Real power is the capacity of the circuit for performing work while apparent power is the product of the current and voltage of the circuit. Industrial plants usually run at a naturally lagging or lower power factor (i.e., the load is inductive in nature). Leading or high power factor means the load is capacitive in nature, while unity power factor, a power factor of 1, is neither leading nor lagging and is the most efficient point for real power transmission. A load with a low power factor draws more current than a load with a power factor closer to 1 for the same amount of power transferred. In an industrial application, such as a factory, a low power factor results in higher amounts of energy lost in the system as well as increased monetary charges by electrical utility companies. Therefore, power factor correction is very important in industrial applications.
Power factor correction may be achieved by adding or removing reactor components such as capacitors or inductors to the power system. Adding capacitors or inductors to the system as needed may bring the power factor closer to 1. As indicated above, too little power factor correction can increase utility bills and cause low voltage problems. Too much correction can contribute to system instability and high voltages. However, present power factor correction systems are very expensive and require the use of specialty hardware including centralized and specialized monitoring systems and complicated control electronics.
Accordingly, a need exists for controllers and systems for power factor correction and monitoring in industrial power systems.